How long should I let printer targets dry before reading them to create profiles?
Short answer from Lou Dina:
Matte Papers using matte black ink ~ 24 hours minimum.
Photo Papers using gloss black ink ~ 8 hours minimum (preferably 12 hours).
Short answer from Valdas:
I usually waiting 24 hours for all papers at least. Measurements after a few days I still get color changes of about 0.1-0.3 delta E compared with measurements after 24 hours.
Long answer(original research by Lou Dina):
I did some testing to see how long it takes Canon inks (iPF6100) to cure and become stable. I did this mainly to help me decide how long to wait before reading test targets for profiling. I chose a smooth matte fine art paper, and also a luster photo paper, since they behave differently and use a different black inks. I used an Eye One Pro UV spectrophotometer and read numerous patches over a period of time.
1. Matte Fine Art Paper (matte black ink)- it takes awhile for inks to cure on matte papers, but the good news is that they continue to darken for better Dmax over time. This is a good thing, because matte papers generally have a weak Dmax compared to Photo papers. The paper tested was a weak paper, which I knew up front, so these results are not representative of better papers. Right out of the printer, the blackest black recorded was 1.55. It took about 24 to 30 hours to stabilize, and the Dmax reading climbed to 1.61, which is quite an improvement. I have seen similar trends with other matte fine art papers. Simply drying overnight (ie, 8 to 12 hours) wasn't adequate time to stabilize.
2. Luster Photo Paper (gloss black ink) - photo papers seem to cure faster, in about 8 hours, though 12 hours would be safer. Photo papers actually LOSE Dmax as they dry and get slightly lighter. This isn't just the blacks, but also colors that don't have any black ink, so it more how the paper reacts with the ink. I don't find this troubling, since photo papers generally have a very black Dmax to begin with. In fact, I like it, because it means those bright light colors become brighter for extended dynamic range and help in those lighter pastels, which are so hard to reproduce in print. Right after printing, I got a Dmax of 2.34, and after 8 hours, it read 2.27. This is not spectro error, since I read every hour or two and saw a gradual, consistent lightening.
I didn't do it on this test, but in the past I have used hair dryers, microwaves, or both to speed the drying process. While that does accelerate the drying cycle, it doesn't replace time. In fact, that is why I ran this test....I reread some of my old targets (dried impatiently with a hair dryer or microwave) and found that they had dried down even more, which concerned me. (I generally write many readings down on my charts, so the original reference data were still there).
I usually print a test strip with 8 or 10 different media settings to pick the best one for printing my profiling target. I noted is that different ink loads tend to dry at different rates, so you really do need adequate time to let them all dry before assessing which one gives you the best performance. It can sometimes change over time, and what looked like the best media setting after 3 hours no longer is after 24 hours. This isn't always the case, but I have seen it.
So, my personal guidelines for ink drying time before profiling (or even settling on a media setting) are:
Matte Papers using matte black ink ~ 24 hours minimum.
Photo Papers using gloss black ink ~ 8 hours minimum (preferably 12 hours).
How long should I let printer targets dry before reading them to create profiles?
Short answer from Lou Dina:
Matte Papers using matte black ink ~ 24 hours minimum.
Photo Papers using gloss black ink ~ 8 hours minimum (preferably 12 hours).
Short answer from Valdas:
I usually waiting 24 hours for all papers at least. Measurements after a few days I still get color changes of about 0.1-0.3 delta E compared with measurements after 24 hours.
Long answer (original research by Lou Dina):
I did some testing to see how long it takes Canon inks (iPF6100) to cure and become stable. I did this mainly to help me decide how long to wait before reading test targets for profiling. I chose a smooth matte fine art paper, and also a luster photo paper, since they behave differently and use a different black inks. I used an Eye One Pro UV spectrophotometer and read numerous patches over a period of time.
1. Matte Fine Art Paper (matte black ink)- it takes awhile for inks to cure on matte papers, but the good news is that they continue to darken for better Dmax over time. This is a good thing, because matte papers generally have a weak Dmax compared to Photo papers. The paper tested was a weak paper, which I knew up front, so these results are not representative of better papers. Right out of the printer, the blackest black recorded was 1.55. It took about 24 to 30 hours to stabilize, and the Dmax reading climbed to 1.61, which is quite an improvement. I have seen similar trends with other matte fine art papers. Simply drying overnight (ie, 8 to 12 hours) wasn't adequate time to stabilize.
2. Luster Photo Paper (gloss black ink) - photo papers seem to cure faster, in about 8 hours, though 12 hours would be safer. Photo papers actually LOSE Dmax as they dry and get slightly lighter. This isn't just the blacks, but also colors that don't have any black ink, so it more how the paper reacts with the ink. I don't find this troubling, since photo papers generally have a very black Dmax to begin with. In fact, I like it, because it means those bright light colors become brighter for extended dynamic range and help in those lighter pastels, which are so hard to reproduce in print. Right after printing, I got a Dmax of 2.34, and after 8 hours, it read 2.27. This is not spectro error, since I read every hour or two and saw a gradual, consistent lightening.
I didn't do it on this test, but in the past I have used hair dryers, microwaves, or both to speed the drying process. While that does accelerate the drying cycle, it doesn't replace time. In fact, that is why I ran this test....I reread some of my old targets (dried impatiently with a hair dryer or microwave) and found that they had dried down even more, which concerned me. (I generally write many readings down on my charts, so the original reference data were still there).
I usually print a test strip with 8 or 10 different media settings to pick the best one for printing my profiling target. I noted is that different ink loads tend to dry at different rates, so you really do need adequate time to let them all dry before assessing which one gives you the best performance. It can sometimes change over time, and what looked like the best media setting after 3 hours no longer is after 24 hours. This isn't always the case, but I have seen it.
So, my personal guidelines for ink drying time before profiling (or even settling on a media setting) are:
Matte Papers using matte black ink ~ 24 hours minimum.
Photo Papers using gloss black ink ~ 8 hours minimum (preferably 12 hours).